JP3594721B2

JP3594721B2 - Surface-coated flaky powder, method for producing the same, and cosmetics incorporating the same

Info

Publication number: JP3594721B2
Application number: JP1947196A
Authority: JP
Inventors: 龍三小林
Original assignee: Noevir Co Ltd
Current assignee: Noevir Co Ltd
Priority date: 1996-01-09
Filing date: 1996-01-09
Publication date: 2004-12-02
Anticipated expiration: 2016-01-09
Also published as: JPH09188611A

Description

【０００１】
【発明の属する技術分野】
本発明は、特定の粒子形状を有する劈開化膨潤性層状粘土鉱物の表面を亜鉛酸化物で被覆して成る表面被覆薄片状粉体に関し、中波長（ＵＶＢ）領域の紫外線だけでなく、長波長（ＵＶＡ）領域の紫外線も防御する効果を有する粉体を提供するものである。さらには、劈開化膨潤性層状粘土鉱物の表面で亜鉛酸化物を生成し被覆することを特徴とする、均一に被覆された、ＵＶＢ，ＵＶＡ両領域の紫外線防御効果の高い粉体の製造に関する。
【０００２】
また、上記表面被覆薄片状粉体を配合することにより、分散性が良く、皮膚上での伸びが滑らかであり、青白くならず自然な仕上がりの得られる化粧料、特には粉体化粧料に関する。さらに、上記表面被覆薄片状粉体と紫外線吸収剤を併用することにより、紫外線吸収効果に優れ、しかも安全性の高い化粧料に関する。
【０００３】
【従来の技術】
紫外線には２９０〜３２０ｎｍの波長のＵＶＢ、及び３２０〜４００ｎｍの波長のＵＶＡがある。ＵＶＡは皮膚のたるみの原因となり、ＵＶＢは皮膚癌や皮膚のシワを形成することに関与するといわれている（サンスクリーン剤と皮膚科学，フレグランスジャーナル社，１９９３）。また、最近はＵＶＡが真皮損傷及びシワの形成に関与するといわれている。
【０００４】
そのため、日常の紫外線を防御する目的で様々な紫外線吸収剤及び紫外線防御粉体が研究されている。
【０００５】
たとえば、特開昭４９−４５０には、微粒子二酸化チタンを配合して紫外線防止用化粧料とすることが提案されている。また、特開昭６２−２２８００６には、３６０ｎｍ付近のＵＶＡを効果的に遮蔽できる物質として、微粒子酸化亜鉛が提案されている。さらに、特開昭６１−２５７９０９には、紫外線遮蔽用顔料として、亜鉛系物質を被覆した無機粉体が提案され、また特開平５−１７３２９には、鱗片状顔料の表面をチタン酸化物で被覆し、該チタン酸化物上に亜鉛酸化物を被覆した顔料組成物が報告されている。
【０００６】
さらに、パラジメチルアミノ安息香酸塩やオキシベンゾン等の紫外線吸収剤を配合して高い紫外線防御能を得る試みが成されてきている。
【０００７】
【発明が解決しようとする課題】
しかしながら、これまで提案されてきた紫外線遮蔽用の顔料や紫外線吸収剤は、以下に示すような問題点を有しており、満足すべきものとはいえない。
【０００８】
まず、微粒子二酸化チタンは、紫外線の遮蔽効果を有しているものの、３５０ｎｍ以上のＵＶＡ領域の紫外線の遮蔽効果が小さい。さらに、微粒子二酸化チタンは、紫外線防御効果を発揮する量を配合すると、肌に塗布するときの伸びが重くなり、また仕上がりが青白くなる青光り現象を生じる。
【０００９】
また、３６０ｎｍ付近のＵＶＡを効果的に遮蔽できる微粒子酸化亜鉛は、化粧料に配合した場合、分散性が悪い。さらに、酸化亜鉛を他の粉体に被覆する場合、乾式による処理だけでは、均一に被覆しにくく、紫外線遮蔽効果に難がある。また、酸化亜鉛と酸化チタンを組み合わせて被覆することにより、ＵＶＡ，ＵＶＢともに防御することができるようになるが、酸化チタンによる被覆力が増大したり、仕上がりが青白くなる、伸びが重くなるといった欠点がある。
【００１０】
そこで、高い紫外線防御効果と伸びの良さを合わせ持ち、しかも安全性に優れ、青光りせず自然な化粧仕上がりの得られる化粧料を得ることを本発明の目的とした。
【００１１】
【課題を解決するための手段】
核粒子として劈開化膨潤性層状粘土鉱物を用い亜鉛酸化物を被覆することにより、マイカ，セリサイト，タルク，カオリン等従来用いられてきた板状粉体よりも微細で、亜鉛酸化物を多量に被覆することができ、化粧料に配合した場合、分散性が良好で、ＵＶＢとＵＶＡの両方の紫外線防御効果が高く、伸びが良く、青光りせず自然な仕上がりが得られることを見出し、本発明を完成するに至った。
【００１２】
すなわち本発明は、厚み０．００１〜０．２μｍ、アスペクト比３０〜１００の劈開化した（劈開化）膨潤性層状粘土鉱物の表面を亜鉛酸化物により湿式で被覆してなる表面被覆薄片状粉体であって、劈開化膨潤性層状粘土鉱物の亜鉛酸化物による被覆率が、ＺｎＯ換算で、表面被覆薄片状粉体全体に対して８０重量％以上である、表面被覆薄片状粉体及びその製造方法、またこの粉体を配合することを特徴とする化粧料に関するものである。
【００１３】
本発明において使用される劈開化膨潤性層状粘土鉱物は、その粒子の大きさが、厚み０．００１〜０．２μｍ、アスペクト比３０〜１００の範囲を有する特定の粉体である。この条件を満たす膨潤性層状粘土鉱物としては、スメクタイト類、バーミキュライト類が挙げられ、これらの膨潤性層状粘土鉱物を劈開化して用いる。ここで用いるスメクタイト類の具体例としては、ノントロナイト，バイデライト，モンモリロナイト等のジオクタヘドラルスメクタイト類やサポナイト等のトリオクタヘドラルスメクタイト類が、バーミキュライト類としてはトリオクタヘドラルバーミキュライト等が挙げられる。また、劈開化膨潤性層状粘土鉱物の起源は、合成、天然であることを問わない。
【００１４】
また、本発明において劈開化膨潤性層状粘土鉱物の表面に被覆する亜鉛酸化物とは、酸化亜鉛又は含水酸化亜鉛を意味する。
【００１５】
上記の劈開化膨潤性層状粘土鉱物に被覆する亜鉛酸化物は、粒子径４０〜１００ｎｍのものが好ましい。また、劈開化膨潤性層状粘土鉱物に対する亜鉛酸化物被覆量はＺｎＯ換算で、表面被覆薄片状粉体全体に対して８０重量％以上が好ましい。８０重量％以下では、必要とする紫外線防御効果が得られなくなる。
【００１６】
劈開化膨潤性層状粘土鉱物に対する亜鉛酸化物の被覆方法は、これまで知られた各種方法、たとえば物理化学的な混合摩砕法（乾式、湿式）や化学的な沈着法などが選択され実施されるが、被覆の均一性及び安定性の面から次に示す方法で製造することが好ましい。
【００１７】
劈開化膨潤性層状粘土鉱物を亜鉛塩の加水分解生成物で被覆し、３００〜７００℃で焼成して亜鉛塩の加水分解生成物を亜鉛酸化物にすることにより、表面被覆薄片状粉体を製造する。
【００１８】
上記において、亜鉛塩の加水分解生成物は、水酸化亜鉛もしくは含水酸化亜鉛を意味し、この亜鉛塩の加水分解生成物を焼成することにより、劈開化膨潤性層状粘土鉱物の表面に亜鉛酸化物が生成する。
【００１９】
この劈開化膨潤性層状粘土鉱物への亜鉛塩の加水分解生成物の被覆方法としては、たとえば劈開化膨潤性層状粘土鉱物を含水溶媒に懸濁させ、６０〜９０℃に加熱し、アルカリ水溶液でｐＨ７．５〜１０に維持しながら、その中に亜鉛塩の水溶液を滴下し、劈開化膨潤性層状粘土鉱物の表面に亜鉛塩の加水分解生成物を被覆する。これをろ過、洗浄、乾燥後３００〜７００℃で焼成して亜鉛塩の加水分解生成物を亜鉛酸化物にすることによって、本発明の表面被覆薄片状粉体が得られる。
【００２０】
さらに、劈開化膨潤性層状粘土鉱物への亜鉛塩の加水分解生成物の被覆方法として、劈開化膨潤性層状粘土鉱物を亜鉛塩の水溶液に懸濁させ、６０〜９０℃に加熱し、攪拌しながらアルカリ水溶液を滴下し、劈開化膨潤性層状粘土鉱物の表面に亜鉛塩の加水分解生成物を被覆する。これをろ過、洗浄、乾燥後３００〜７００℃で焼成して亜鉛塩の加水分解生成物を亜鉛酸化物にすることによっても、本発明の表面被覆薄片状粉体が得られる。
【００２１】
劈開化膨潤性層状粘土鉱物を懸濁する含水溶媒及び亜鉛塩の水溶液は、必要に応じてｐＨ調整剤、分散剤、分散助剤、粘度調整剤等を添加することができる。また、劈開化膨潤性層状粘土鉱物と含水溶媒及び亜鉛塩の水溶液の比は、含水溶媒及び亜鉛塩の水溶液１リットルに対して１０〜３００ｇが好ましい。
【００２２】
上記亜鉛酸化物の被覆に際して使用する亜鉛塩としては、たとえば硫酸亜鉛、塩化亜鉛、酢酸亜鉛などが挙げられる。
【００２３】
アルカリ水溶液のアルカリ源としては、水酸化ナトリウム，水酸化カリウムなどのアルカリ金属の水酸化物、アンモニア水やアミン類、尿素等が用いられる。
【００２４】
また、得られた表面被覆薄片状粉体をシリコーン化合物、有機フッ素化合物、高級脂肪酸、金属セッケン、ワックス、ペースト等の疎水性化合物でさらに被覆することにより、化粧料に配合した場合、分散性及び化粧持ちが向上する。
【００２５】
表面被覆薄片状粉体を疎水性化合物で処理する場合、その処理は、粉体製造時に行っても良く、また他の粉体と混合した後でも良い。
【００２６】
また、表面被覆薄片状粉体を疎水性化合物で処理する際の表面被覆薄片状粉体と疎水性化合物の重量比は、表面被覆薄片状粉体の表面積が大きいため、表面を均一に処理するには、１００／２以上、好ましくは１００／４以上の割合で処理する必要がある。
【００２７】
さらに、表面被覆薄片状粉体と併用する紫外線吸収剤としては、通常化粧料に配合される紫外線吸収剤であれば、特に限定されない。具体例としては、パラアミノ安息香酸エチル，パラジメチルアミノ安息香酸エチルヘキシル等のパラアミノ安息香酸エステル類、パラ−メトキシ桂皮酸−２−エトキシエチル，パラメトキシ桂皮酸エチルヘキシル等のパラメトキシ桂皮酸エステル類といった中波長域紫外線（ＵＶＢ）吸収剤、４−ｔ−ブチル−４’−メトキシベンゾイルメタン等のジベンゾイルメタン類、２−ヒドロキシ−４−メトキシベンゾフェノン等のオキシベンゾン類といった長波長域紫外線（ＵＶＡ）吸収剤を用いることができる。
【００２８】
また、表面被覆薄片状粉体を、微粒子酸化チタン，酸化亜鉛，酸化チタン被覆粉体，微粒子酸化鉄等、他の紫外線防御性粉体と併用することもできる。
【００２９】
【発明の実施の形態】
このようにして得られた表面被覆薄片状粉体を、化粧料に配合する。化粧料への配合量としては、０．１〜５０重量％が好ましく、さらに好ましくは１〜３０重量％である。このようにして得られる化粧料としては、リキッドファンデーション，パウダーファンデーション，ケーキファンデーション，スティックファンデーション，フェイスパウダー，口紅，頬紅，アイシャドウ，アイブロウペンシルなどのメイクアップ化粧料を中心として、その他ボディパウダー，制汗剤，日焼け止めクリーム，日焼け止め乳液，美白パウダー，乳液，化粧水など幅広いものが例示される。そして上記化粧料中でもとりわけ、パウダータイプ或いはツーウェイタイプのケーキ型ファンデーション，アイカラー，チークカラー，ハイライトカラー，シャドウカラー，粉白粉，固形白粉等の粉体化粧料では、皮膚にのばすときの感触及び化粧仕上がり効果が最も顕著であり本発明の化粧料として最適である。
【００３０】
さらに、上記メイクアップ化粧料が、粉体固形化粧料もしくは油性化粧料である場合には、疎水性化合物で処理した表面被覆薄片状粉体を配合することにより、分散性がさらに向上し、しかも化粧持ちが良好となる。
【００３１】
表面被覆薄片状粉体と紫外線吸収剤を併用することにより、相乗的に紫外線防御効果が向上し、しかも安全性に優れたものとなる。
【００３２】
【実施例】
さらに、本発明について実施例により詳細に説明する。
【００３３】
実施例１：亜鉛酸化物処理スメクタイト
１Ｎ硫酸亜鉛７水和塩水溶液１リットルに、アスペクト比７０，厚み０．０７μｍのスメクタイト２０ｇを懸濁攪拌し、８０℃に加熱後、２Ｎ水酸化ナトリウム水溶液９８３ｍｌを９０分で滴下した。ついで、これをろ過、水洗、乾燥、粉砕後、５００℃で２時間焼成して、表面を亜鉛酸化物で被覆したスメクタイト１００ｇを得た。
【００３４】
実施例２：亜鉛酸化物処理モンモリロナイト
アスペクト比６０，厚み０．１μｍのモンモリロナイト３０ｇを５００ｍｌの水に懸濁し、７５℃に加熱する。攪拌しながら４Ｎ塩化亜鉛水溶液１リットルを１２０分で滴下した。この間、ｐＨを９に保つために、１Ｎの水酸化カリウムを滴下した。これをろ過、水洗、乾燥、粉砕後、４５０℃で３時間焼成して、表面を亜鉛酸化物で被覆したモンモリロナイト３５０ｇを得た。
【００３５】
実施例３：シリコーン被覆亜鉛酸化物処理スメクタイト
実施例１で製造した亜鉛酸化物処理スメクタイト９６部とメチルハイドロジェンポリシロキサン４部を混合し、１２０℃で４時間加熱し、シリコーン被覆亜鉛酸化物処理スメクタイトを得た。
【００３６】
比較例１
アスペクト比７０，厚み０．０７μｍのスメクタイト２０ｇと、比表面積７０ｍ^２／ｇの微粒子酸化亜鉛を振動ボールミルで１２０分間処理して酸化亜鉛被覆スメクタイト１００ｇを得た。
【００３７】
比較例２
平均粒子径５μｍで、アスペクト比６のスメクタイトを用いて実施例１と同様に処理後焼成し、表面を亜鉛酸化物で被覆したスメクタイト１００ｇを得た。
【００３８】
本発明の表面被覆薄片状粉体の紫外線防御効果をＳＰＦアナライザー（ＳＰＦ２９０ＡＮＡＬＹＺＥＲ：ＯｐｔｏｍｅｔｏｒｉｃｓＵＳＡ，Ｉｎｃ社製）を用いて測定した。測定は薄いシリコーン膜を形成させたトランスポアテープ（住友スリーエム社製）を石英板上に接着させ、これに試料０．５ｍｇ／ｃｍ^２をブラシを用いて塗布したものを用いて行った。実施例１〜３及び比較例１，２の表面被覆薄片状粉体を試料として上記の装置及び方法で測定を行い、得られたＳＰＦ及び平均ＵＶＡ防御指数（ＵＶＡＰＦ，ＡｖｅｒａｇｅＵＶＡＰｒｏｔｅｃｔｉｏｎＦａｃｔｏｒ）を表１に示した。
【表１】

【００３９】
表１に示すように、本発明の実施例１〜３の表面被覆薄片状粉体は、ＳＰＦ及びＵＶＡＰＦ共に高い値となり、ＵＶＢ，ＵＶＡ領域の両方の波長の紫外線を防御する効果に優れていることがわかる。一方、酸化亜鉛とスメクタイトを乾式で処理した比較例１、及び粒径の大きいスメクタイトに亜鉛酸化物を被覆した比較例２では、ＳＰＦ及びＵＶＡＰＦともに、実施例の２分の１以下であった。
【００４０】
また図１は、実施例１の粉体を試料として、ＳＰＦアナライザーを用いて、各波長の紫外線の透過量を測定した結果であり、透過量の逆数をＭＰＦとして表した。実施例１は、ＵＶＡ領域の３６０ｎｍ付近、及びＵＶＢ領域の３２０ｎｍ付近に吸収極大を有するため、ＵＶＡ，ＵＶＢ両方の波長の紫外線から皮膚を防御し、しかも４００ｎｍ以上の可視領域にはほとんど吸収がなく透明性の高い粉体であることが示された。
【００４１】
次に実施例１〜３及び比較例１，２の粉体を走査型電子顕微鏡を用いて観察した。その結果、実施例１〜３では、劈開化膨潤性層状粘土鉱物の表面に亜鉛酸化物が均一に被覆されていた。しかしながら、比較例１，２の粉体は、劈開化膨潤性層状粘土鉱物の表面に均一に酸化亜鉛及び亜鉛酸化物が被覆されずに、スメクタイト表面に多層に被覆しているものが存在し、また酸化亜鉛及び亜鉛酸化物が遊離し、部分的に凝集が認められた。
【００４２】
次に、本発明に係る粉体、実施例１〜３を化粧料に配合した実施例を示す。
【００４３】
実施例４：パウダーファンデーション

製法：（１）〜（６）の成分を混合機中で混合均一化した後（７）の成分を噴霧しさらに混合する。次いで粉砕機を通して粉砕した後、金皿に充填し圧縮成形する。
【００４４】
実施例５：ツーウェイファンデーション

製法：（１）〜（６）を混合機で混合均一化した後、（７）〜（９）の成分を加熱溶解した油相を添加し、混合機で混合均一化する。次いで粉砕機を通して粉砕した後、金皿に充填し圧縮成形する。
【００４５】
実施例６：固形白粉

製法：（１）〜（７）の成分を混合機中で混合均一化した後、混合均一化した（８）〜（１０）の成分を噴霧しさらに混合する。次いで粉砕機を通して粉砕した後、金皿に充填し圧縮成形する。
【００４６】
実施例７：スティック状ファンデーション

製法：（１）〜（６）の成分を混合機で混合均一化した粉体相を得る。別に（７）〜（１５）の成分を混合し、８０℃で加熱して融解した油相を得る。加熱した油相に先の粉体相を加え、ロールミルで混練する。混練したものを加熱し、型又は容器に流し込み冷却して成形する。
【００４７】
実施例８：日焼け止め乳液

製法：（８）〜（１１）の成分をホモミキサーで予備乳化し、水相を得る。（１）〜（７）の成分を７５℃に加熱均一化した後、７５℃に加熱した水相成分に添加し、ホモミキサーを用いて乳化する。４０℃まで攪拌冷却した後、（１２）及び（１３）の成分を添加する。
【００４８】
実施例９：粉白粉

製法：（１）〜（６）の成分を混合機中で混合均一化した後、混合均一化した（７），（８）の成分を噴霧しさらに混合する。次いで粉砕機を通して粉砕した後、篩を通して製品とする。
【００４９】
実施例１０：油中水型日焼け止めクリーム

製法：（１０）〜（１２）の成分をホモミキサーで予備乳化し、水相を得る。（１）〜（７）の成分を７５℃に加熱均一化した後、７５℃に加熱した水相成分を添加し、ホモミキサーを用いて乳化する。攪拌しながら室温まで冷却し、油中水型乳化日焼け止めクリームを得る。
【００５０】
さらに、本発明の実施例４〜８における紫外線防御効果を示すために、ＳｕｎＰｒｏｔｅｃｔｉｏｎＦａｃｔｏｒ（ＳＰＦ）を測定した。ＳＰＦは、光源としてキセノンアークソーラーシュミレーターを用い、成人男子１０名を被験者とし、あらかじめ試料未塗布部の最小紅斑量（ＭＥＤ）を求めた後、試料の予想ＳＰＦ値以上の照射を公比１．３で５段階行い、試料塗布部のＭＥＤを求め、試料塗布部の値を試料未塗布部の値で除してＳＰＦを算出し、各被験者の平均値により表した。また同時に表面被覆薄片状粉体のかわりに微粒子酸化亜鉛を配合したものをそれぞれ比較例４〜８とした。結果を表２に示す。
【表２】

【００５１】
表２より、各実施例は比較例の１．５〜２．２倍の高いＳＰＦを有しており、微粒子の亜鉛酸化物を劈開化膨潤性層状粘土鉱物に被覆して配合することにより、亜鉛酸化物の分散性が良好になり高い紫外線防御効果が得られることが示された。特に実施例５及び７では、比較例の２倍以上の高いＳＰＦ値を有しており、本発明による表面被覆薄片状粉体と紫外線吸収剤を併用することによる相乗効果が示された。
【００５２】
また、本発明の実施例４〜８及び比較例４〜８を用いて使用感評価を行った。評価項目は伸び、青光り、白浮きの３項目で、専門パネル５名で評価し、評点の人数分布を表３に示す。
【表３】

【００５３】
表３より、実施例は比較例よりも、伸びが良く青光りや白浮きを生じないことは明らかである。また、各実施例使用者においてアレルギー反応を起こしたり、刺激感を訴えたパネルはいなかった。
【００５４】
【発明の効果】
以上に述べたとおり、本発明により、ＵＶＢのみならずＵＶＡ領域の紫外線も同時に防御できる機能性の高い粉体を得ることができた。また、この粉体を配合した化粧料は、高い紫外線防御効果と伸びの良さを有し、安全性に優れ、青光りせず自然な化粧仕上がりが得られた。さらに、紫外線吸収剤と併用すると、相乗的に紫外線防御効果が向上することが認められた。
【図面の簡単な説明】
【図１】実施例１の粉体の紫外線遮蔽効果を示す図である[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surface-coated flaky powder obtained by coating the surface of a cleaved swellable layered clay mineral having a specific particle shape with zinc oxide, and relates to not only ultraviolet light in the medium wavelength (UVB) region but also long wavelength light. An object of the present invention is to provide a powder having an effect of protecting ultraviolet rays in the (UVA) region. Furthermore, the present invention relates to the production of a uniformly coated powder having a high UV protection effect in both the UVB and UVA regions, which is characterized by forming and coating zinc oxide on the surface of the cleaved swellable layered clay mineral.
[0002]
In addition, the present invention relates to a cosmetic which has good dispersibility, has a smooth elongation on the skin, and has a natural finish without becoming pale, and particularly a powder cosmetic by blending the surface-coated flaky powder. Further, the present invention relates to a cosmetic composition which is excellent in ultraviolet absorption effect and high in safety by using the above surface-coated flaky powder and an ultraviolet absorber in combination.
[0003]
[Prior art]
Ultraviolet light includes UVB having a wavelength of 290 to 320 nm and UVA having a wavelength of 320 to 400 nm. UVA causes sagging of the skin, and UVB is said to be involved in the formation of skin cancer and skin wrinkles (Sunscreen and Dermatology, Fragrance Journal, 1993). It has recently been said that UVA is involved in dermis damage and wrinkle formation.
[0004]
Therefore, various UV absorbers and UV protection powders have been studied for the purpose of protecting everyday UV rays.
[0005]
For example, Japanese Patent Application Laid-Open No. 49-450 proposes that a fine particle titanium dioxide be blended into a cosmetic for preventing ultraviolet rays. Japanese Patent Application Laid-Open No. 62-228006 proposes particulate zinc oxide as a substance that can effectively block UVA near 360 nm. Furthermore, JP-A-61-257909 proposes an inorganic powder coated with a zinc-based substance as an ultraviolet shielding pigment, and JP-A-5-17329 discloses that a flaky pigment is coated with titanium oxide. However, a pigment composition in which zinc oxide is coated on the titanium oxide has been reported.
[0006]
Further, attempts have been made to obtain high ultraviolet protection ability by blending an ultraviolet absorber such as paradimethylaminobenzoate or oxybenzone.
[0007]
[Problems to be solved by the invention]
However, the pigments and ultraviolet absorbers for ultraviolet shielding that have been proposed so far have the following problems, and cannot be said to be satisfactory.
[0008]
First, although the particulate titanium dioxide has an effect of shielding ultraviolet rays, the effect of shielding ultraviolet rays in the UVA region of 350 nm or more is small. Furthermore, when the amount of the fine particle titanium dioxide which exerts an ultraviolet ray protective effect is blended, the elongation at the time of application to the skin becomes heavy, and a bluish phenomenon occurs in which the finish becomes pale.
[0009]
Fine zinc oxide particles that can effectively block UVA near 360 nm have poor dispersibility when incorporated into cosmetics. Further, when zinc oxide is coated on other powders, it is difficult to uniformly coat the powder by a dry treatment alone, and there is a difficulty in an ultraviolet shielding effect. Also, by coating with a combination of zinc oxide and titanium oxide, both UVA and UVB can be protected, but the drawbacks are that the coating power of titanium oxide increases, the finish becomes pale, and the elongation increases. There is.
[0010]
Accordingly, it is an object of the present invention to provide a cosmetic that has both a high UV protection effect and good elongation, is excellent in safety, and does not emit blue light and can provide a natural cosmetic finish.
[0011]
[Means for Solving the Problems]
By coating the zinc oxide with a cleaved swellable layered clay mineral as the core particle, it is finer than the conventionally used plate-like powders such as mica, sericite, talc, kaolin, and has a large amount of zinc oxide. It was found that it can be coated and, when blended into cosmetics, has good dispersibility, has a high UV protection effect of both UVB and UVA, has good elongation, and gives a natural finish without bluish light. The invention has been completed.
[0012]
That is, the present invention has a thickness 0.001～0.2Myuemu, was cleaved of aspect ratio 30 to 100 (cleavage of) surface-coated flaky coated with wet-ing the zinc oxide surface of the swellable layered clay mineral A surface-coated flaky powder, wherein the coating ratio of the cleaved swellable layered clay mineral with zinc oxide is 80% by weight or more based on the total weight of the surface-coated flaky powder in terms of ZnO; The present invention relates to a method for producing the composition, and a cosmetic characterized by incorporating the powder.
[0013]
The cleaved swellable layered clay mineral used in the present invention is a specific powder having a particle size of 0.001 to 0.2 μm and an aspect ratio of 30 to 100. Examples of the swellable layered clay mineral satisfying this condition include smectites and vermiculites, and these swellable layered clay minerals are cleaved and used. Specific examples of the smectites used herein include dioctahedral smectites such as nontronite, beidellite and montmorillonite, and trioctahedral smectites such as saponite, and the vermiculite includes trioctahedral vermiculite. Can be The origin of the cleaved swellable layered clay mineral may be synthetic or natural.
[0014]
In the present invention, the zinc oxide covering the surface of the cleaved swellable layered clay mineral refers to zinc oxide or hydrous zinc oxide.
[0015]
The zinc oxide coated on the cleavage-swelling layered clay mineral preferably has a particle diameter of 40 to 100 nm. Further, the amount of the zinc oxide coating on the cleaved swellable layered clay mineral is preferably 80% by weight or more based on the whole surface-coated flaky powder in terms of ZnO. If it is less than 80% by weight, the required ultraviolet protection effect cannot be obtained.
[0016]
As a method of coating the cleaved swellable layered clay mineral with zinc oxide, various methods known so far, for example, a physicochemical mixed grinding method (dry or wet method) or a chemical deposition method are selected and performed. However, from the viewpoints of uniformity and stability of the coating, it is preferable to produce it by the following method.
[0017]
The surface-coated flaky powder is obtained by coating the cleaved swellable layered clay mineral with a hydrolysis product of a zinc salt and firing at 300 to 700 ° C. to convert the hydrolysis product of the zinc salt into zinc oxide. To manufacture.
[0018]
In the above, the hydrolysis product of the zinc salt means zinc hydroxide or hydrated zinc oxide. By calcining the hydrolysis product of the zinc salt, the surface of the cleaved swellable layered clay mineral is coated with zinc oxide. Is generated.
[0019]
As a method of coating the cleavage product of the hydrolysis product of the zinc salt on the cleaved swellable layered clay mineral, for example, the cleaved swellable layered clay mineral is suspended in a water-containing solvent, heated to 60 to 90 ° C., and treated with an alkaline aqueous solution. While maintaining the pH at 7.5 to 10, an aqueous solution of a zinc salt is dropped therein, and the surface of the cleaved swellable layered clay mineral is coated with the hydrolysis product of the zinc salt. This is filtered, washed, dried and then calcined at 300 to 700 ° C. to convert the zinc salt hydrolysis product into zinc oxide, whereby the surface-coated flaky powder of the present invention is obtained.
[0020]
Further, as a method of coating the cleavage product of the hydrolysis product of the zinc salt on the cleaved swellable layered clay mineral, the cleaved swellable layered clay mineral is suspended in an aqueous solution of a zinc salt, heated to 60 to 90 ° C., and stirred. While the alkaline aqueous solution is dropped, the surface of the cleaved swellable layered clay mineral is coated with a hydrolysis product of a zinc salt. This is filtered, washed, dried and then calcined at 300 to 700 ° C. to convert the zinc salt hydrolysis product into zinc oxide, whereby the surface-coated flaky powder of the present invention can be obtained.
[0021]
If necessary, a pH adjusting agent, a dispersing agent, a dispersing aid, a viscosity adjusting agent and the like can be added to the aqueous solvent and the aqueous solution of the zinc salt in which the cleaved swellable layered clay mineral is suspended. The ratio of the cleaved swellable layered clay mineral to the aqueous solution of the aqueous solvent and the zinc salt is preferably from 10 to 300 g per liter of the aqueous solution of the aqueous solvent and the zinc salt.
[0022]
Examples of the zinc salt used for coating the zinc oxide include zinc sulfate, zinc chloride, and zinc acetate.
[0023]
As the alkali source of the aqueous alkali solution, hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide, aqueous ammonia, amines, urea and the like are used.
[0024]
In addition, when the obtained surface-coated flaky powder is further coated with a hydrophobic compound such as a silicone compound, an organic fluorine compound, a higher fatty acid, a metal soap, a wax, and a paste, the dispersibility and Makeup lasts longer.
[0025]
When the surface-coated flaky powder is treated with a hydrophobic compound, the treatment may be performed at the time of powder production or after mixing with another powder.
[0026]
When the surface-coated flaky powder is treated with a hydrophobic compound, the weight ratio between the surface-coated flaky powder and the hydrophobic compound is such that the surface is uniformly treated because the surface-coated flaky powder has a large surface area. Requires treatment at a rate of 100/2 or more, preferably 100/4 or more.
[0027]
Further, the ultraviolet absorber used in combination with the surface-coated flaky powder is not particularly limited as long as it is an ultraviolet absorber usually blended in cosmetics. Specific examples include a medium wavelength region such as paraaminobenzoic acid esters such as ethyl paraaminobenzoate and ethylhexyl paradimethylaminobenzoate, and paramethoxycinnamic acid esters such as 2-ethoxyethyl para-methoxycinnamate and ethylhexyl paramethoxycinnamate. Uses ultraviolet (UVA) absorbers such as ultraviolet (UVB) absorbers, dibenzoylmethanes such as 4-t-butyl-4'-methoxybenzoylmethane, and oxybenzones such as 2-hydroxy-4-methoxybenzophenone. be able to.
[0028]
Further, the surface-coated flaky powder can be used in combination with other ultraviolet protective powders such as fine particle titanium oxide, zinc oxide, titanium oxide coated powder, and fine particle iron oxide.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
The surface-coated flaky powder thus obtained is blended into a cosmetic. The compounding amount in the cosmetic is preferably 0.1 to 50% by weight, and more preferably 1 to 30% by weight. Cosmetic products obtained in this manner include liquid cosmetics, powder foundations, cake foundations, stick foundations, face powders, lipsticks, blushers, eye shadows, eyebrow pencils, and other makeup powders. Examples include a wide variety such as sweats, sunscreen creams, sunscreen emulsions, whitening powders, emulsions and lotions. Among the above-mentioned cosmetics, powder cosmetics such as powder type or two-way type cake type foundations, eye color, cheek color, highlight color, shadow color, powdered white powder, and solid white powder have the following effects on skin. The cosmetic finish effect is most remarkable and is optimal as the cosmetic of the present invention.
[0030]
Furthermore, when the makeup cosmetic is a powdered solid cosmetic or an oily cosmetic, dispersibility is further improved by blending a surface-coated flaky powder treated with a hydrophobic compound, and The makeup lasts well.
[0031]
The combined use of the surface-coated flaky powder and the ultraviolet absorber synergistically enhances the ultraviolet protection effect and provides excellent safety.
[0032]
【Example】
Further, the present invention will be described in detail with reference to examples.
[0033]
Example 1 20 g of smectite having an aspect ratio of 70 and a thickness of 0.07 μm was suspended and stirred in 1 liter of a 1N aqueous solution of zinc oxide-treated smectite 1N zinc sulfate heptahydrate, heated to 80 ° C. and then 983 ml of a 2N aqueous sodium hydroxide solution. Was added dropwise in 90 minutes. Then, this was filtered, washed with water, dried, pulverized, and calcined at 500 ° C. for 2 hours to obtain 100 g of smectite whose surface was coated with zinc oxide.
[0034]
Example 2 Zinc Oxide Treated Montmorillonite 30 g of montmorillonite having an aspect ratio of 60 and a thickness of 0.1 μm is suspended in 500 ml of water and heated to 75 ° C. While stirring, 1 liter of a 4N aqueous zinc chloride solution was added dropwise over 120 minutes. During this time, 1N potassium hydroxide was added dropwise to keep the pH at 9. This was filtered, washed with water, dried, pulverized, and calcined at 450 ° C. for 3 hours to obtain 350 g of montmorillonite whose surface was coated with zinc oxide.
[0035]
Example 3: Silicone-coated zinc oxide-treated smectite 96 parts of the zinc oxide-treated smectite prepared in Example 1 and 4 parts of methylhydrogenpolysiloxane were mixed and heated at 120 ° C for 4 hours to be treated with the silicone-coated zinc oxide. Smectite was obtained.
[0036]
Comparative Example 1
20 g of smectite having an aspect ratio of 70 and a thickness of 0.07 μm and fine zinc oxide having a specific surface area of 70 m ² / g were subjected to a vibration ball mill for 120 minutes to obtain 100 g of smectite coated with zinc oxide.
[0037]
Comparative Example 2
Using a smectite having an average particle diameter of 5 μm and an aspect ratio of 6, the same treatment as in Example 1 was followed by baking to obtain 100 g of smectite whose surface was coated with zinc oxide.
[0038]
The ultraviolet protection effect of the surface-coated flaky powder of the present invention was measured using an SPF analyzer (SPF290 ANALYZER: manufactured by Optometrics USA, Inc.). The measurement was carried out by using a transpore tape (manufactured by Sumitomo 3M) having a thin silicone film adhered to a quartz plate and applying a 0.5 mg / cm ² sample to the quartz plate using a brush. Using the surface-coated flaky powders of Examples 1 to 3 and Comparative Examples 1 and 2 as samples, the measurement was carried out by the above apparatus and method, and the obtained SPF and average UVA protection index (UVAPF, Average UVA Protection Factor) were tabulated. 1 is shown.
[Table 1]

[0039]
As shown in Table 1, the surface-coated flaky powders of Examples 1 to 3 of the present invention have high values for both SPF and UVAPF, and are excellent in the effect of protecting ultraviolet rays of both wavelengths in the UVB and UVA regions. You can see that. On the other hand, in Comparative Example 1 in which zinc oxide and smectite were dry-processed and in Comparative Example 2 in which smectite having a large particle diameter was coated with zinc oxide, both SPF and UVAPF were less than half of the examples.
[0040]
FIG. 1 shows the results of measurement of the amount of transmission of ultraviolet light of each wavelength using the powder of Example 1 as a sample using an SPF analyzer, and the reciprocal of the amount of transmission is expressed as MPF. Example 1 has an absorption maximum around 360 nm in the UVA region and around 320 nm in the UVB region, and thus protects the skin from ultraviolet rays of both UVA and UVB wavelengths, and has almost no absorption in the visible region of 400 nm or more. It was shown that the powder had high transparency.
[0041]
Next, the powders of Examples 1 to 3 and Comparative Examples 1 and 2 were observed using a scanning electron microscope. As a result, in Examples 1 to 3, the surface of the cleaved swellable layered clay mineral was uniformly coated with zinc oxide. However, the powders of Comparative Examples 1 and 2 were not uniformly coated with zinc oxide and zinc oxide on the surface of the cleaved and swellable layered clay mineral, and there were powders having a multi-layered coating on the smectite surface, Further, zinc oxide and zinc oxide were released, and partial aggregation was observed.
[0042]
Next, an example is shown in which the powder according to the present invention, Examples 1 to 3, are blended into a cosmetic.
[0043]
Example 4: Powder foundation

Production method: After the components (1) to (6) are mixed and homogenized in a mixer, the component (7) is sprayed and further mixed. Next, after pulverizing through a pulverizer, the mixture is filled in a metal plate and compression molded.
[0044]
Example 5: Two-way foundation

Production method: After (1) to (6) are mixed and homogenized by a mixer, an oil phase obtained by heating and dissolving the components (7) to (9) is added, and the mixture is homogenized by the mixer. Next, after pulverizing through a pulverizer, the mixture is filled in a metal plate and compression molded.
[0045]
Example 6: Solid white powder

Production method: After the components (1) to (7) are mixed and homogenized in a mixer, the components (8) to (10) that have been mixed and homogenized are sprayed and further mixed. Next, after pulverizing through a pulverizer, the mixture is filled in a metal plate and compression molded.
[0046]
Example 7: Stick foundation

Production method: A powder phase is obtained by mixing and homogenizing the components (1) to (6) with a mixer. Separately, the components (7) to (15) are mixed and heated at 80 ° C. to obtain a molten oil phase. The powder phase is added to the heated oil phase and kneaded with a roll mill. The kneaded product is heated, poured into a mold or a container, cooled and molded.
[0047]
Example 8: Sunscreen emulsion

Production method: The components (8) to (11) are pre-emulsified with a homomixer to obtain an aqueous phase. After the components (1) to (7) are heated and homogenized to 75 ° C, they are added to the aqueous phase component heated to 75 ° C, and emulsified using a homomixer. After stirring and cooling to 40 ° C., the components (12) and (13) are added.
[0048]
Example 9: White powder

Production method: After the components (1) to (6) are mixed and homogenized in a mixer, the components (7) and (8) that have been mixed and homogenized are sprayed and further mixed. Next, after pulverizing through a pulverizer, a product is passed through a sieve.
[0049]
Example 10: Water-in-oil sunscreen cream

Production method: The components (10) to (12) are pre-emulsified with a homomixer to obtain an aqueous phase. After the components (1) to (7) are heated and homogenized to 75 ° C., the aqueous phase component heated to 75 ° C. is added and emulsified using a homomixer. Cool to room temperature with stirring to obtain a water-in-oil emulsion sunscreen.
[0050]
Furthermore, in order to show the ultraviolet protection effect in Examples 4 to 8 of the present invention, Sun Protection Factor (SPF) was measured. The SPF uses a xenon arc solar simulator as a light source, and subjects 10 adult males as subjects to determine the minimum erythema amount (MED) of the uncoated portion of the sample in advance. The MED of the sample-applied portion was determined by dividing the value of the sample-applied portion by the value of the sample-unapplied portion to calculate the SPF, which was represented by the average value of each subject. At the same time, Comparative Examples 4 to 8 were prepared by blending fine particle zinc oxide instead of the surface-coated flaky powder. Table 2 shows the results.
[Table 2]

[0051]
From Table 2, each example has 1.5 to 2.2 times higher SPF than the comparative example. By coating zinc oxide of fine particles on the cleaved swellable layered clay mineral and blending the same, It was shown that the dispersibility of zinc oxide was improved and a high ultraviolet protection effect was obtained. In particular, in Examples 5 and 7, the SPF value was twice or more as high as that of the comparative example, and a synergistic effect was obtained by using the surface-coated flaky powder according to the present invention and an ultraviolet absorber in combination.
[0052]
In addition, usability evaluation was performed using Examples 4 to 8 and Comparative Examples 4 to 8 of the present invention. The evaluation items were three items, elongation, bluish glow, and white floating, which were evaluated by five specialized panels.
[Table 3]

[0053]
From Table 3, it is clear that the examples have better elongation than the comparative examples and do not cause bluish or whitening. In addition, there was no panel that caused an allergic reaction or a feeling of irritation in the users of the examples.
[0054]
【The invention's effect】
As described above, according to the present invention, a highly functional powder capable of simultaneously protecting not only UVB but also UV light in the UVA region can be obtained. In addition, the cosmetic containing this powder had a high UV protection effect and good elongation, was excellent in safety, and obtained a natural cosmetic finish without shining blue. Furthermore, it was recognized that when used in combination with an ultraviolet absorber, the ultraviolet protection effect was synergistically improved.
[Brief description of the drawings]
FIG. 1 is a view showing an ultraviolet shielding effect of a powder of Example 1.

Claims

Thickness 0.001～0.2Myuemu, a surface-coated flaky powder ing covered with wet the surface of the zinc oxide of the swellable layered clay mineral was cleaved of aspect ratio 30 to 100, and cleavage of A surface-coated flaky powder, wherein the coverage of the swellable layered clay mineral with zinc oxide is 80% by weight or more based on the total weight of the surface-coated flaky powder in terms of ZnO .

Cleavage of the swellable layered clay mineral is one or more selected from smectite and vermiculite such surface coating flaky powder according to claim 1.

A surface-coated flaky powder, wherein the surface of the surface-coated flaky powder according to claim 1 or 2 is further coated with a hydrophobic compound.

The cleavage of the swelling clay mineral coated with hydrolysis product of a zinc salt, characterized in that the hydrolysis product of zinc oxide calcined to zinc salt at 300 to 700 ° C., according to claim 1 or 3. The method for producing a surface-coated flaky powder according to 2 .

A cosmetic comprising the surface-coated flaky powder according to any one of claims 1 to 3 .

The cosmetic according to claim 5, which is a sunscreen cosmetic or a powder cosmetic .

The cosmetic according to claim 5 , wherein an ultraviolet absorber is used in combination.